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Offshore Dispersant Data and Decisions

Critical Review of the Literature Seeks to Ease the Understanding of Data Used in the Decision Process for Offshore Dispersant Use

COLUMBIA, S.C. — Dispersants are often used in oil spill responses because they may mitigate
the environmental impacts of the spill by moving the oil from the water surface into the water
column enhancing its biodegradation. While this process helps reduce the likelihood of oil
exposure to marine wildlife such as seabirds and marine mammals, aquatic toxicity on marine
communities from the dispersant and the chemically dispersed oil needs to be considered more
carefully.

Scientists at Research Planning, Inc. and HDR Ecosystem Management evaluated the standard
toxicity testing data used to inform dispersant decisions and published a critical review of their
findings in the scientific journal Environmental Toxicology and Chemistry in March 2014. The
authors found issues with the current practices, and lead author Adriana Bejarano notes, “Despite
concerted efforts by the spill response community to propose and promote discussions on better
laboratory practices, studies are still performed without consideration of such recommendations.”
Laboratory tests frequently used by decision makers do not adequately replicate the conditions in
the field, such as sea state and weather, nor do they necessarily consider exposure durations
(short-term vs. standard exposure) and concentrations (steady concentrations vs. spiked
concentrations).

Bejarano’s goal was to bring to light some of the common misconceptions and challenges in
existing data, and to encourage decision makers to consider data quality when making decisions
on the use of dispersants. “Data comparability is difficult because of the mixed messages coming
from the scientific literature. Many believe that dispersants make oil more toxic, when in reality
existing data generally do not support these claims. Being critical would be beneficial to the
entire decision-making process.”

About the journal: Published on behalf of the Society of Environmental Toxicology and Chemistry (SETAC), Environmental Toxicology and Chemistry is dedicated to furthering
scientific knowledge and disseminating information on environmental toxicology and chemistry,
including the application of these sciences to risk assessment.